SV40 has been shown to have adjuvant-like action since it enhances cytolytic T cell activity in allogeneically-primed mice. The virus has a somewhat specific effect on cell-mediated immune responses since cytotoxic T, but not helper T function, is increased. Conversely, Complete Freund's Adjuvant (CFA) has been shown to increase helper T but not cytotoxic T cell function. The cellular basis for adjuvant action is currently under investigation. BIBLIOGRAPHIC REFERENCES: Reinisch, C.L., Gleiner, N.A. and Schlossman, S.F.: Adjuvant regulation of T cell function. (In press, J. Immunol., for March, 1976). Bhan, A.K., Reinisch, C.L., Levey, R.H., McCluskey, R.T. and Schlossman, S.F.: T-cell migration into allografts. J. Exp. Med. 141: 1210, 1975.